diff --git a/.gitignore b/.gitignore
index 41278df..8c1d213 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,7 @@ setuptools-*
 dist
 build
 eggs
+.eggs
 parts
 bin
 var
diff --git a/Adafruit_IO/_version.py b/Adafruit_IO/_version.py
index 239bf2b..528787c 100644
--- a/Adafruit_IO/_version.py
+++ b/Adafruit_IO/_version.py
@@ -1 +1 @@
-__version__ = "2.8.2"
+__version__ = "3.0.0"
diff --git a/Adafruit_IO/client.py b/Adafruit_IO/client.py
index 3f92326..9562aa7 100644
--- a/Adafruit_IO/client.py
+++ b/Adafruit_IO/client.py
@@ -22,7 +22,14 @@
 from time import struct_time
 import json
 import platform
-import pkg_resources
+try:
+    from importlib.metadata import version as package_version  # Python 3.8+
+except ImportError:
+    try:
+        from importlib_metadata import version as package_version  # Backport for <3.8
+    except ImportError:  # pragma: no cover - fallback for older Python
+        package_version = None
+        import pkg_resources
 import re
 from urllib.parse import urlparse
 from urllib.parse import parse_qs
@@ -35,8 +42,11 @@
 
 DEFAULT_PAGE_LIMIT = 100
 
-# set outgoing version, pulled from setup.py
-version = pkg_resources.require("Adafruit_IO")[0].version
+# set outgoing version, pulled from package metadata
+if package_version is not None:
+    version = package_version("Adafruit_IO")
+else:
+    version = pkg_resources.require("Adafruit_IO")[0].version
 default_headers = {
     'User-Agent': 'AdafruitIO-Python/{0} ({1}, {2} {3})'.format(version,
                                                                 platform.platform(),
diff --git a/Adafruit_IO/mqtt_client.py b/Adafruit_IO/mqtt_client.py
index 198b4d6..ef9a53e 100644
--- a/Adafruit_IO/mqtt_client.py
+++ b/Adafruit_IO/mqtt_client.py
@@ -19,6 +19,7 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 import logging
+import re
 
 import paho.mqtt.client as mqtt
 import sys
@@ -35,6 +36,25 @@
                   "forecast_hours_24", "forecast_days_1",
                   "forecast_days_2", "forecast_days_5",]
 
+
+def validate_feed_key(feed_key):
+    """Validates a provided feed key against Adafruit IO's system rules.
+    https://learn.adafruit.com/naming-things-in-adafruit-io/the-two-feed-identifiers
+    
+    :param str feed_key: The feed key to validate.
+    :raises ValueError: If the feed key is too long.
+    :raises TypeError: If the feed key contains invalid characters or is empty.
+    """
+    if len(feed_key) > 128:  # validate feed key length
+        raise ValueError("Feed key must be less than 128 characters.")
+    if not bool(
+        re.match(r"^[a-zA-Z0-9-]+((\/|\.)[a-zA-Z0-9-]+)?$", feed_key)
+    ):  # validate key naming scheme
+        raise TypeError(
+            "Feed key must contain English letters, numbers, dash, and a period or a forward slash."
+        )
+
+
 class MQTTClient(object):
     """Interface for publishing and subscribing to feed changes on Adafruit IO
     using the MQTT protocol.
@@ -198,21 +218,22 @@ def loop(self, timeout_sec=1.0):
         """
         self._client.loop(timeout=timeout_sec)
 
-    def subscribe(self, feed_id, feed_user=None, qos=0):
+    def subscribe(self, feed_key, feed_user=None, qos=0):
         """Subscribe to changes on the specified feed.  When the feed is updated
-        the on_message function will be called with the feed_id and new value.
+        the on_message function will be called with the feed_key and new value.
 
-        :param str feed_id: The key of the feed to subscribe to.
+        :param str feed_key: The key of the feed to subscribe to.
         :param str feed_user: Optional, identifies feed owner. Used for feed sharing.
         :param int qos: The QoS to use when subscribing. Defaults to 0.
 
         """
+        validate_feed_key(feed_key)
         if qos > 1:
             raise MQTTError("Adafruit IO only supports a QoS level of 0 or 1.")
         if feed_user is not None:
-            (res, mid) = self._client.subscribe('{0}/feeds/{1}'.format(feed_user, feed_id, qos=qos))
+            (res, mid) = self._client.subscribe('{0}/feeds/{1}'.format(feed_user, feed_key), qos=qos)
         else:
-            (res, mid) = self._client.subscribe('{0}/feeds/{1}'.format(self._username, feed_id), qos=qos)
+            (res, mid) = self._client.subscribe('{0}/feeds/{1}'.format(self._username, feed_key), qos=qos)
         return res, mid
 
     def subscribe_group(self, group_id, qos=0):
@@ -264,43 +285,45 @@ def subscribe_time(self, time):
             raise TypeError('Invalid Time Feed Specified.')
             return
     
-    def unsubscribe(self, feed_id=None, group_id=None):
+    def unsubscribe(self, feed_key=None, group_id=None):
       """Unsubscribes from a specified MQTT topic.
       Note: this does not prevent publishing to a topic, it will unsubscribe
       from receiving messages via on_message.
       """
-      if feed_id is not None:
-        self._client.unsubscribe('{0}/feeds/{1}'.format(self._username, feed_id))
+      if feed_key is not None:
+        validate_feed_key(feed_key)
+        self._client.unsubscribe('{0}/feeds/{1}'.format(self._username, feed_key))
       elif group_id is not None:
         self._client.unsubscribe('{0}/groups/{1}'.format(self._username, group_id))
       else:
         raise TypeError('Invalid topic type specified.')
         return
 
-    def receive(self, feed_id):
+    def receive(self, feed_key):
       """Receive the last published value from a specified feed.
 
-      :param string feed_id: The ID of the feed to update.
-      :parm string value: The new value to publish to the feed
+      :param string feed_key: The key of the feed to retrieve the value from.
       """
-      (res, self._pub_mid) = self._client.publish('{0}/feeds/{1}/get'.format(self._username, feed_id),
+      validate_feed_key(feed_key)
+      (res, self._pub_mid) = self._client.publish('{0}/feeds/{1}/get'.format(self._username, feed_key),
           payload='')
 
-    def publish(self, feed_id, value=None, group_id=None, feed_user=None):
+    def publish(self, feed_key, value=None, group_id=None, feed_user=None):
         """Publish a value to a specified feed.
 
         Params:
-        - feed_id: The id of the feed to update.
+        - feed_key: The key of the feed to update.
         - value: The new value to publish to the feed.
         - (optional) group_id: The id of the group to update. 
         - (optional) feed_user: The feed owner's username. Used for Sharing Feeds.
         """
+        validate_feed_key(feed_key)
         if feed_user is not None: # shared feed
-          (res, self._pub_mid) = self._client.publish('{0}/feeds/{1}'.format(feed_user, feed_id),
+          (res, self._pub_mid) = self._client.publish('{0}/feeds/{1}'.format(feed_user, feed_key),
               payload=value)
         elif group_id is not None: # group-specified feed
-          self._client.publish('{0}/feeds/{1}.{2}'.format(self._username, group_id, feed_id),
+          self._client.publish('{0}/feeds/{1}.{2}'.format(self._username, group_id, feed_key),
               payload=value)
         else: # regular feed
-          (res, self._pub_mid) = self._client.publish('{0}/feeds/{1}'.format(self._username, feed_id),
+          (res, self._pub_mid) = self._client.publish('{0}/feeds/{1}'.format(self._username, feed_key),
               payload=value)
diff --git a/examples/api/data.py b/examples/api/data.py
index 63df954..4805e31 100644
--- a/examples/api/data.py
+++ b/examples/api/data.py
@@ -2,18 +2,21 @@
 # API client.
 # Author: Tony Dicola, Justin Cooper
 
-# Import Adafruit IO REST client.
-from Adafruit_IO import Client, Feed, Data, RequestError
+# Import standard python modules.
 import datetime
+import os
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
+# Import Adafruit IO REST client.
+from Adafruit_IO import Client, Feed, Data, RequestError
 
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/api/feeds.py b/examples/api/feeds.py
index 848bdda..1047498 100644
--- a/examples/api/feeds.py
+++ b/examples/api/feeds.py
@@ -2,18 +2,20 @@
 # API client.
 # Author: Tony Dicola, Justin Cooper, Brent Rubell
 
+# Import standard python modules.
+import os
+
 # Import Adafruit IO REST client.
 from Adafruit_IO import Client, Feed
-import json
-
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
 
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/api/location.py b/examples/api/location.py
index 3e5846a..b2cf2cf 100644
--- a/examples/api/location.py
+++ b/examples/api/location.py
@@ -7,17 +7,20 @@
 Author(s): Brent Rubell
 """
 
+# Import standard python modules.
+import os
+
 # Import Adafruit IO REST client.
 from Adafruit_IO import Client, Feed, RequestError
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/api/random_data.py b/examples/api/random_data.py
index 719e026..edda90c 100644
--- a/examples/api/random_data.py
+++ b/examples/api/random_data.py
@@ -6,14 +6,20 @@
 
 Author(s): Brent Rubell for Adafruit Industries
 """
-# Import JSON for forecast parsing
+# Import standard python modules
 import json
+import os
 # Import Adafruit IO REST client.
-from Adafruit_IO import Client, Feed, RequestError
+from Adafruit_IO import Client
+
+# Set to your Adafruit IO username.
+# (go to https://accounts.adafruit.com to find your username)
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_IO_USERNAME')
 
 # Set to your Adafruit IO key.
-ADAFRUIT_IO_USERNAME = 'YOUR_IO_USERNAME'
-ADAFRUIT_IO_KEY = 'YOUR_IO_KEY'
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_IO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/api/simple.py b/examples/api/simple.py
index 2f7de33..2ec5326 100644
--- a/examples/api/simple.py
+++ b/examples/api/simple.py
@@ -2,17 +2,20 @@
 # API client.
 # Author: Tony DiCola
 
+# Import standard python modules.
+import os
+
 # Import Adafruit IO REST client.
 from Adafruit_IO import Client, RequestError, Feed
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/api/weather.py b/examples/api/weather.py
index 3e4bc5c..7307821 100644
--- a/examples/api/weather.py
+++ b/examples/api/weather.py
@@ -6,14 +6,22 @@
 
 Author(s): Brent Rubell for Adafruit Industries
 """
-# Import JSON for forecast parsing
+
+# Import JSON for forecast parsing, os for environment variables.
 import json
+import os
+
 # Import Adafruit IO REST client.
-from Adafruit_IO import Client, Feed, RequestError
+from Adafruit_IO import Client
+
+# Set to your Adafruit IO username.
+# (go to https://accounts.adafruit.com to find your username)
+ADAFRUIT_IO_USERNAME = os.getenv("ADAFRUIT_IO_USERNAME", "YOUR_IO_USERNAME")
 
 # Set to your Adafruit IO key.
-ADAFRUIT_IO_USERNAME = 'YOUR_IO_USERNAME'
-ADAFRUIT_IO_KEY = 'YOUR_IO_PASSWORD'
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv("ADAFRUIT_IO_KEY", "YOUR_IO_PASSWORD")
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
@@ -24,18 +32,28 @@
 forecast = json.loads(weather)
 
 # Parse the current forecast
-current = forecast['current']
-print('Current Forecast')
-print('It is {0} and {1}.'.format(current['summary'], current['temperature']))
+current = forecast["current"]
+print("Current Forecast")
+print("It is {0} and {1}.".format(current["summary"], current["temperature"]))
 
 # Parse the two day forecast
-forecast_days_2 = forecast['forecast_days_2']
-print('\nWeather in Two Days')
-print('It will be {0} with a high of {1}F and a low of {2}F.'.format(
-            forecast_days_2['summary'], forecast_days_2['temperatureLow'], forecast_days_2['temperatureHigh']))
+forecast_days_2 = forecast["forecast_days_2"]
+print("\nWeather in Two Days")
+print(
+    "It will be {0} with a high of {1}F and a low of {2}F.".format(
+        forecast_days_2["summary"],
+        forecast_days_2["temperatureLow"],
+        forecast_days_2["temperatureHigh"],
+    )
+)
 
 # Parse the five day forecast
-forecast_days_5 = forecast['forecast_days_5']
-print('\nWeather in Five Days')
-print('It will be {0} with a high of {1}F and a low of {2}F.'.format(
-            forecast_days_5['summary'], forecast_days_5['temperatureLow'], forecast_days_5['temperatureHigh']))
\ No newline at end of file
+forecast_days_5 = forecast["forecast_days_5"]
+print("\nWeather in Five Days")
+print(
+    "It will be {0} with a high of {1}F and a low of {2}F.".format(
+        forecast_days_5["summary"],
+        forecast_days_5["temperatureLow"],
+        forecast_days_5["temperatureHigh"],
+    )
+)
diff --git a/examples/basics/analog_in.py b/examples/basics/analog_in.py
index 14f73f4..5b0e75f 100644
--- a/examples/basics/analog_in.py
+++ b/examples/basics/analog_in.py
@@ -13,6 +13,7 @@
         (https://github.com/adafruit/Adafruit_CircuitPython_MCP3xxx)
 """
 # Import standard python modules
+import os
 import time
 
 # import Adafruit Blinka
@@ -27,14 +28,14 @@
 from adafruit_mcp3xxx.mcp3008 import MCP3008
 from adafruit_mcp3xxx.analog_in import AnalogIn
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 # Create an instance of the REST client
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
 
diff --git a/examples/basics/analog_output.py b/examples/basics/analog_output.py
index a1d2994..f04a1e8 100644
--- a/examples/basics/analog_output.py
+++ b/examples/basics/analog_output.py
@@ -22,6 +22,7 @@
 """
 
 # import system libraries
+import os
 import time
 
 # import Adafruit Blinka
@@ -34,14 +35,14 @@
 # import Adafruit IO REST client
 from Adafruit_IO import Client, Feed, RequestError
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_IO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_IO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_IO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_IO_KEY')
 
 # Create the I2C bus interface.
 i2c_bus = I2C(SCL, SDA)
diff --git a/examples/basics/dashboard.py b/examples/basics/dashboard.py
index 8a5bc61..a2619bd 100644
--- a/examples/basics/dashboard.py
+++ b/examples/basics/dashboard.py
@@ -5,18 +5,19 @@
 
 Author(s): Doug Zobel
 """
+import os
 from time import sleep
 from random import randrange
 from Adafruit_IO import Client, Feed, Block, Dashboard, Layout
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_USERNAME = ''
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_KEY = ''
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', '')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', '')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
@@ -27,7 +28,7 @@
 # Fetch group info (group.id needed when adding feeds to blocks)
 group = aio.groups("default")
 
-# Create a new dasbhoard named 'Example Dashboard'
+# Create a new dashboard named 'Example Dashboard'
 dashboard = aio.create_dashboard(Dashboard(name="Example Dashboard"))
 
 # Create a line_chart
@@ -36,6 +37,7 @@
                   properties = {
                       "gridLines": True,
                       "historyHours": "2"},
+                  # block_feeds expects a numeric feed_id, not the feed key
                   block_feeds = [{
                       "group_id": group.id,
                       "feed_id":  feed.id
diff --git a/examples/basics/digital_in.py b/examples/basics/digital_in.py
index c4a40c0..d83cd19 100644
--- a/examples/basics/digital_in.py
+++ b/examples/basics/digital_in.py
@@ -7,6 +7,7 @@
 Author(s): Brent Rubell, Todd Treece
 """
 # Import standard python modules
+import os
 import time
 
 # import Adafruit Blinka
@@ -16,14 +17,14 @@
 # import Adafruit IO REST client.
 from Adafruit_IO import Client, Feed, RequestError
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/basics/digital_out.py b/examples/basics/digital_out.py
index 5da4f99..4773693 100644
--- a/examples/basics/digital_out.py
+++ b/examples/basics/digital_out.py
@@ -7,6 +7,7 @@
 Author(s): Brent Rubell, Todd Treece
 """
 # Import standard python modules
+import os
 import time
 
 # import Adafruit Blinka
@@ -16,14 +17,14 @@
 # import Adafruit IO REST client.
 from Adafruit_IO import Client, Feed, RequestError
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
@@ -42,7 +43,7 @@
 while True:
     try:
         data = aio.receive(digital.key)
-    except RequestError as re:
+    except RequestError:
         pass  # feed with no data will return 404
     if int(data.value) == 1:
         print('received <- ON\n')
diff --git a/examples/basics/location.py b/examples/basics/location.py
index c772a9c..a4688d0 100644
--- a/examples/basics/location.py
+++ b/examples/basics/location.py
@@ -7,19 +7,20 @@
 Author(s): Brent Rubell, Todd Treece
 """
 # Import standard python modules
+import os
 import time
 
 # Import Adafruit IO REST client.
 from Adafruit_IO import Client, Feed, RequestError
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/basics/neopixel.py b/examples/basics/neopixel.py
index 5c6b241..b74067b 100644
--- a/examples/basics/neopixel.py
+++ b/examples/basics/neopixel.py
@@ -20,6 +20,7 @@
     - Adafruit_CircuitPython_NeoPixel
         (https://github.com/adafruit/Adafruit_CircuitPython_NeoPixel)
 """
+import os
 import time
 import board
 import neopixel
@@ -39,14 +40,14 @@
     pixel_pin, num_pixels, brightness=0.2, auto_write=False, pixel_order=ORDER
 )
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/basics/pi_camera.py b/examples/basics/pi_camera.py
index 4fd26ec..c8e18ce 100644
--- a/examples/basics/pi_camera.py
+++ b/examples/basics/pi_camera.py
@@ -6,12 +6,12 @@
 Adafruit IO feed.
 """
 # import standard python modules
-import time
 import base64
 import os
+import time
 
 # import Adafruit IO REST client
-from Adafruit_IO import Client, Feed, RequestError
+from Adafruit_IO import Client
 
 # import raspberry pi camera module
 import picamera
@@ -19,14 +19,14 @@
 # camera capture interval, in seconds
 CAMERA_INTERVAL = 3
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
@@ -56,7 +56,8 @@
     try:
       aio.send(picam_feed.key, image_string)
       print('Picture sent to Adafruit IO')
-    except:
+    except Exception as e:
       print('Sending to Adafruit IO Failed...')
+      print('Error:', e)
 
   time.sleep(CAMERA_INTERVAL)
diff --git a/examples/basics/publish.py b/examples/basics/publish.py
index 6498ee3..47984f7 100644
--- a/examples/basics/publish.py
+++ b/examples/basics/publish.py
@@ -6,6 +6,7 @@
 Author(s): Brent Rubell, Todd Treece for Adafruit Industries
 """
 # Import standard python modules
+import os
 import time
 
 # Import Adafruit IO REST client.
@@ -14,14 +15,14 @@
 # holds the count for the feed
 run_count = 0
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/basics/rgb_led.py b/examples/basics/rgb_led.py
index 06781bf..9ae06cf 100644
--- a/examples/basics/rgb_led.py
+++ b/examples/basics/rgb_led.py
@@ -22,6 +22,7 @@
         (https://github.com/adafruit/Adafruit_CircuitPython_PCA9685)
 """
 # import system libraries
+import os
 import time
 
 # import Adafruit Blinka
@@ -39,14 +40,14 @@
 GREEN_PIN = 5
 BLUE_PIN = 4
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/basics/servo.py b/examples/basics/servo.py
index 54ee95f..f1fe086 100644
--- a/examples/basics/servo.py
+++ b/examples/basics/servo.py
@@ -24,6 +24,7 @@
 """
 
 # import system libraries
+import os
 import time
 
 # import Adafruit Blinka
@@ -41,12 +42,12 @@
 
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
 
 # Set to your Adafruit IO key.
 # Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/basics/subscribe.py b/examples/basics/subscribe.py
index f9661f6..f80d153 100644
--- a/examples/basics/subscribe.py
+++ b/examples/basics/subscribe.py
@@ -6,22 +6,23 @@
 Author(s): Brent Rubell, Todd Treece for Adafruit Industries
 """
 # Import standard python modules.
+import os
 import sys
 
 # This example uses the MQTTClient instead of the REST client
 from Adafruit_IO import MQTTClient
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
-# Set to the ID of the feed to subscribe to for updates.
-FEED_ID = 'counter'
+# Set to the key of the feed to subscribe to for updates.
+FEED_KEY = 'counter'
 
 # Define callback functions which will be called when certain events happen.
 def connected(client):
@@ -31,20 +32,20 @@ def connected(client):
     can make calls against it easily.
     """
     # Subscribe to changes on a feed named Counter.
-    print('Subscribing to Feed {0}'.format(FEED_ID))
-    client.subscribe(FEED_ID)
+    print('Subscribing to Feed {0}'.format(FEED_KEY))
+    client.subscribe(FEED_KEY)
     print('Waiting for feed data...')
 
 def disconnected(client):
     """Disconnected function will be called when the client disconnects."""
     sys.exit(1)
 
-def message(client, feed_id, payload):
+def message(client, feed_key, payload):
     """Message function will be called when a subscribed feed has a new value.
-    The feed_id parameter identifies the feed, and the payload parameter has
+    The feed_key parameter identifies the feed, and the payload parameter has
     the new value.
     """
-    print('Feed {0} received new value: {1}'.format(feed_id, payload))
+    print('Feed {0} received new value: {1}'.format(feed_key, payload))
 
 
 # Create an MQTT client instance.
diff --git a/examples/basics/temp_humidity.py b/examples/basics/temp_humidity.py
index 618d5f6..3d76894 100644
--- a/examples/basics/temp_humidity.py
+++ b/examples/basics/temp_humidity.py
@@ -15,6 +15,7 @@
 """
 
 # import standard python modules.
+import os
 import time
 
 # import adafruit-blinka modules
@@ -32,14 +33,14 @@
 # Time between sensor reads, in seconds
 READ_TIMEOUT = 60
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username).
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
@@ -71,7 +72,7 @@
         print('Temp={0:0.1f}*F'.format(temperature))
     else:
         print('Temp={0:0.1f}*C'.format(temperature))
-    print('Humidity={1:0.1f}%'.format(humidity))
+    print('Humidity={0:0.1f}%'.format(humidity))
     # Format sensor data as string for sending to Adafruit IO
     temperature = '%.2f'%(temperature)
     humidity = '%.2f'%(humidity)
diff --git a/examples/basics/time.py b/examples/basics/time.py
index a6204c8..a29349c 100644
--- a/examples/basics/time.py
+++ b/examples/basics/time.py
@@ -9,17 +9,20 @@
 
 Author: Brent Rubell
 """
-# Import Adafruit IO REST client.
-from Adafruit_IO import Client, Feed, Data, RequestError
+# Import standard python modules.
+import os
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
+# Import Adafruit IO REST client.
+from Adafruit_IO import Client
 
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Create an instance of the REST client.
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
diff --git a/examples/basics/type-conversion.py b/examples/basics/type-conversion.py
index 4ccb729..86a6647 100644
--- a/examples/basics/type-conversion.py
+++ b/examples/basics/type-conversion.py
@@ -8,17 +8,20 @@
 Author(s): Brent Rubell, Todd Treece for Adafruit Industries
 """
 
+# import standard python modules.
+import os
+
 # import Adafruit IO REST client.
 from Adafruit_IO import Client, Feed, RequestError
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 aio = Client(ADAFRUIT_IO_USERNAME, ADAFRUIT_IO_KEY)
 
diff --git a/examples/mqtt/mqtt_client_class.py b/examples/mqtt/mqtt_client_class.py
index e7a16ff..583c7ad 100644
--- a/examples/mqtt/mqtt_client_class.py
+++ b/examples/mqtt/mqtt_client_class.py
@@ -2,6 +2,7 @@
 # Author: Tony DiCola
 
 # Import standard python modules.
+import os
 import random
 import sys
 import time
@@ -9,14 +10,14 @@
 # Import Adafruit IO MQTT client.
 from Adafruit_IO import MQTTClient
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 
 # Define callback functions which will be called when certain events happen.
@@ -34,11 +35,11 @@ def disconnected(client):
     print('Disconnected from Adafruit IO!')
     sys.exit(1)
 
-def message(client, feed_id, payload):
+def message(client, feed_key, payload):
     # Message function will be called when a subscribed feed has a new value.
-    # The feed_id parameter identifies the feed, and the payload parameter has
+    # The feed_key parameter identifies the feed, and the payload parameter has
     # the new value.
-    print('Feed {0} received new value: {1}'.format(feed_id, payload))
+    print('Feed {0} received new value: {1}'.format(feed_key, payload))
 
 
 # Create an MQTT client instance.
diff --git a/examples/mqtt/mqtt_groups_pubsub.py b/examples/mqtt/mqtt_groups_pubsub.py
index cf69963..27241ed 100644
--- a/examples/mqtt/mqtt_groups_pubsub.py
+++ b/examples/mqtt/mqtt_groups_pubsub.py
@@ -4,6 +4,7 @@
 # Author: Brent Rubell for Adafruit Industries, 2018
 
 # Import standard python modules.
+import os
 import random
 import sys
 import time
@@ -11,14 +12,14 @@
 # Import Adafruit IO MQTT client.
 from Adafruit_IO import MQTTClient
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Group Name
 group_name = 'grouptest'
diff --git a/examples/mqtt/mqtt_shared_feeds.py b/examples/mqtt/mqtt_shared_feeds.py
index 23b2f16..bdc3cc2 100644
--- a/examples/mqtt/mqtt_shared_feeds.py
+++ b/examples/mqtt/mqtt_shared_feeds.py
@@ -9,6 +9,7 @@
 """
 
 # Import standard python modules.
+import os
 import sys
 import time
 import random
@@ -16,14 +17,14 @@
 # Import Adafruit IO MQTT client.
 from Adafruit_IO import MQTTClient
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 # Shared IO Feed
 # Make sure you have read AND write access to this feed to publish.
@@ -45,12 +46,12 @@ def disconnected(client):
     print('Disconnected from Adafruit IO!')
     sys.exit(1)
 
-def message(client, feed_id, payload):
+def message(client, feed_key, payload):
     """Message function will be called when a subscribed feed has a new value.
-    The feed_id parameter identifies the feed, and the payload parameter has
+    The feed_key parameter identifies the feed, and the payload parameter has
     the new value.
     """
-    print('Feed {0} received new value: {1}'.format(feed_id, payload))
+    print('Feed {0} received new value: {1}'.format(feed_key, payload))
 
 
 # Create an MQTT client instance.
diff --git a/examples/mqtt/mqtt_subscribe.py b/examples/mqtt/mqtt_subscribe.py
index e3b2999..0b92471 100644
--- a/examples/mqtt/mqtt_subscribe.py
+++ b/examples/mqtt/mqtt_subscribe.py
@@ -3,22 +3,24 @@
 # username, and feed to subscribe to for changes.
 
 # Import standard python modules.
+import os
 import sys
 
 # Import Adafruit IO MQTT client.
 from Adafruit_IO import MQTTClient
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
-# Set to the ID of the feed to subscribe to for updates.
-FEED_ID = 'DemoFeed'
+# Set to the key of the feed to subscribe to for updates.
+# Create this feed in your Adafruit IO account and then publish some values
+FEED_KEY = 'DemoFeed'
 
 
 # Define callback functions which will be called when certain events happen.
@@ -27,24 +29,28 @@ def connected(client):
     # This is a good place to subscribe to feed changes.  The client parameter
     # passed to this function is the Adafruit IO MQTT client so you can make
     # calls against it easily.
-    print('Connected to Adafruit IO!  Listening for {0} changes...'.format(FEED_ID))
+    print(
+        "Connected to Adafruit IO as {0}!  Listening for {1} changes...".format(
+            ADAFRUIT_IO_USERNAME, FEED_KEY
+        )
+    )
     # Subscribe to changes on a feed named DemoFeed.
-    client.subscribe(FEED_ID)
+    client.subscribe(FEED_KEY)
 
 def subscribe(client, userdata, mid, granted_qos):
     # This method is called when the client subscribes to a new feed.
-    print('Subscribed to {0} with QoS {1}'.format(FEED_ID, granted_qos[0]))
+    print('Subscribed to {0} with QoS {1}'.format(FEED_KEY, granted_qos[0]))
 
 def disconnected(client):
     # Disconnected function will be called when the client disconnects.
     print('Disconnected from Adafruit IO!')
     sys.exit(1)
 
-def message(client, feed_id, payload):
+def message(client, feed_key, payload):
     # Message function will be called when a subscribed feed has a new value.
-    # The feed_id parameter identifies the feed, and the payload parameter has
+    # The feed_key parameter identifies the feed, and the payload parameter has
     # the new value.
-    print('Feed {0} received new value: {1}'.format(feed_id, payload))
+    print('Feed {0} received new value: {1}'.format(feed_key, payload))
 
 
 # Create an MQTT client instance.
diff --git a/examples/mqtt/mqtt_time.py b/examples/mqtt/mqtt_time.py
index 19875d3..b643458 100644
--- a/examples/mqtt/mqtt_time.py
+++ b/examples/mqtt/mqtt_time.py
@@ -8,31 +8,32 @@
 """
 
 # Import standard python modules.
+import os
 import sys
 import time
 
 # Import Adafruit IO MQTT client.
 from Adafruit_IO import MQTTClient
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'YOUR_AIO_KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'YOUR_AIO_USERNAME'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'YOUR_AIO_USERNAME')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'YOUR_AIO_KEY')
 
 def disconnected(client):
     # Disconnected function will be called when the client disconnects.
     print('Disconnected from Adafruit IO!')
     sys.exit(1)
 
-def message(client, feed_id, payload):
+def message(client, feed_key, payload):
     # Message function will be called when a subscribed feed has a new value.
-    # The feed_id parameter identifies the feed, and the payload parameter has
+    # The feed_key parameter identifies the feed, and the payload parameter has
     # the new value.
-    print('\t Feed {0} received new value: {1}'.format(feed_id, payload))
+    print('\t Feed {0} received new value: {1}'.format(feed_key, payload))
 
 
 # Create a SECURE MQTT client instance
diff --git a/examples/mqtt/mqtt_weather.py b/examples/mqtt/mqtt_weather.py
index 9d148d4..244e64d 100644
--- a/examples/mqtt/mqtt_weather.py
+++ b/examples/mqtt/mqtt_weather.py
@@ -9,20 +9,21 @@
 """
 
 # Import standard python modules.
-import sys
 import json
+import os
+import sys
 
 # Import Adafruit IO MQTT client.
 from Adafruit_IO import MQTTClient
 
-# Set to your Adafruit IO key.
-# Remember, your key is a secret,
-# so make sure not to publish it when you publish this code!
-ADAFRUIT_IO_KEY = 'KEY'
-
 # Set to your Adafruit IO username.
 # (go to https://accounts.adafruit.com to find your username)
-ADAFRUIT_IO_USERNAME = 'USER'
+ADAFRUIT_IO_USERNAME = os.getenv('ADAFRUIT_IO_USERNAME', 'USER')
+
+# Set to your Adafruit IO key.
+# Remember, your key is a secret,
+# so make sure **not** to publish it when you publish this code!
+ADAFRUIT_IO_KEY = os.getenv('ADAFRUIT_IO_KEY', 'KEY')
 
 # Set to ID of the forecast to subscribe to for updates
 forecast_id = 2153
diff --git a/tests/test_mqtt_client.py b/tests/test_mqtt_client.py
index fc611e9..6186bc0 100644
--- a/tests/test_mqtt_client.py
+++ b/tests/test_mqtt_client.py
@@ -22,6 +22,7 @@
 import unittest
 
 from Adafruit_IO import MQTTClient
+from Adafruit_IO.mqtt_client import validate_feed_key
 
 import base
 
@@ -122,4 +123,124 @@ def on_message(mqtt_client, feed, payload):
             client.loop()
             time.sleep(0)
         # Verify one update message with payload is received.
-        self.assertListEqual(messages, [('testfeed', '42')])
\ No newline at end of file
+        self.assertListEqual(messages, [('testfeed', '42')])
+
+
+class TestFeedKeyValidation(unittest.TestCase):
+    """Tests for feed key validation."""
+
+    def test_valid_feed_keys(self):
+        """Test that valid feed keys pass validation."""
+        valid_keys = [
+            'testfeed',
+            'test-feed',
+            'test123',
+            'TESTFEED',
+            'Test-Feed-123',
+            'group.feed',
+            'group/feed',
+            'my-group.my-feed',
+            'my-group/my-feed',
+        ]
+        for key in valid_keys:
+            try:
+                validate_feed_key(key)
+            except (ValueError, TypeError) as e:
+                self.fail(f"Valid feed key '{key}' raised exception: {e}")
+
+    def test_empty_feed_key(self):
+        """Test that empty string raises TypeError due to invalid pattern."""
+        with self.assertRaises(TypeError) as context:
+            validate_feed_key('')
+        self.assertIn('Feed key must contain', str(context.exception))
+
+    def test_feed_key_too_long(self):
+        """Test that feed keys longer than 128 characters raise ValueError."""
+        long_key = 'a' * 129
+        with self.assertRaises(ValueError) as context:
+            validate_feed_key(long_key)
+        self.assertIn('less than 128 characters', str(context.exception))
+
+    def test_feed_key_invalid_characters(self):
+        """Test that feed keys with invalid characters raise TypeError."""
+        invalid_keys = [
+            'test feed',  # space
+            'test_feed',  # underscore
+            'test@feed',  # special character
+            'test!feed',  # special character
+            'test#feed',  # special character
+            'test$feed',  # special character
+        ]
+        for key in invalid_keys:
+            with self.assertRaises(TypeError) as context:
+                validate_feed_key(key)
+            self.assertIn('Feed key must contain', str(context.exception))
+
+    def test_feed_key_invalid_patterns(self):
+        """Test that feed keys with invalid patterns raise TypeError."""
+        invalid_keys = [
+            '.testfeed',  # starts with period
+            '/testfeed',  # starts with slash
+            'test.',      # ends with period
+            'test/',      # ends with slash
+            'test..feed', # double period
+            'test//feed', # double slash
+            'test./feed', # period followed by slash
+            'test/.feed', # slash followed by period
+        ]
+        for key in invalid_keys:
+            with self.assertRaises(TypeError) as context:
+                validate_feed_key(key)
+            self.assertIn('Feed key must contain', str(context.exception))
+
+
+class TestMQTTClientFeedKeyValidation(unittest.TestCase):
+    """Tests for feed key validation in MQTT client methods."""
+
+    def test_subscribe_with_empty_feed_key(self):
+        """Test that subscribe() raises TypeError with empty feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.subscribe('')
+
+    def test_subscribe_with_invalid_feed_key(self):
+        """Test that subscribe() raises TypeError with invalid feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.subscribe('invalid feed')
+
+    def test_publish_with_empty_feed_key(self):
+        """Test that publish() raises TypeError with empty feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.publish('', 42)
+
+    def test_publish_with_invalid_feed_key(self):
+        """Test that publish() raises TypeError with invalid feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.publish('invalid_feed', 42)
+
+    def test_unsubscribe_with_empty_feed_key(self):
+        """Test that unsubscribe() raises TypeError with empty feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.unsubscribe(feed_key='')
+
+    def test_unsubscribe_with_invalid_feed_key(self):
+        """Test that unsubscribe() raises TypeError with invalid feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.unsubscribe(feed_key='test feed')
+
+    def test_receive_with_empty_feed_key(self):
+        """Test that receive() raises TypeError with empty feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.receive('')
+
+    def test_receive_with_invalid_feed_key(self):
+        """Test that receive() raises TypeError with invalid feed key."""
+        client = MQTTClient('testuser', 'testkey')
+        with self.assertRaises(TypeError):
+            client.receive('test@feed')
\ No newline at end of file